Effect of porosity variation strategy on the performance of functionally graded Ti-6Al-4V scaffolds for bone tissue engineering

• Published in: Materials & design 2018-11, Vol.157, p.523-538
• Main Authors: Zhang, Xiang-Yu, Fang, Gang, Xing, Lei-Lei, Liu, Wei, Zhou, Jie
• Format: Article
• Language: English
• Subjects: Functionally graded scaffold; Mechanical properties; Permeability; Selective laser melting; Ti-6Al-4V
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2018.07.064

Functionally graded scaffold (FGS) is designed to mimic the morphology, mechanical and biological properties of natural bone closely. Porosity variation strategy between different regions in FGS plays a crucial role in influencing its mechanical and biological performance. A combination of modeling tool and scripting language can effectively enhance the ability to optimize FGS design. This study was aimed at determining the effect of porosity variation strategy on the mechanical performance and permeability of the as-built and as-heat-treated FGSs. Ti-6Al-4V FGSs with sizes of 10 × 10 × 15 mm and diamond lattice structures were designed and fabricated by means of selective laser melting. A wide range of porosities in the FGSs (38–75%) were achieved by applying six different porosity variation strategies. The elastic modulus (3.7–5.7 GPa) and yield strength (27.1–84.7 MPa) of the as-built FGSs were found to vary between the corresponding mechanical properties of cancellous bone and cortical bone. Heat treatment reduced the strengths by 13–56%. Porosity variation strategy strongly affected the deformation behavior and failure mechanisms of the FGSs. The sigmoid function-controlled FGSs showed gradual failure behavior and sample Sigk0.5b8 showed superior overall performance. The results demonstrated that porosity variation strategy is a feasible means for tailor design of FGS. [Display omitted] •Functionally graded Ti-6Al-4V scaffolds (FGS) with different porosity variation strategies are designed and fabricated.•Young’s modulus and yield strength of the FGS are respectively situated between those of cancellous bone and cortical bone.•Porosity variation strategy strongly affects the permeability, deformation behavior and failure mechanisms of the FGS.•Gradual failure feature of the sigmoid function-controlled FGS under compression avoid its loose fragments.